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Prime-versus-Prime, challenge #2, ROLLOUTS

Posted By: Nack Ballard
Date: Saturday, 18 October 2014, at 4:25 p.m.

In Response To: Prime-versus-Prime, challenge #2 (Nack Ballard)

		White is Player 2 score: 0 pip: 122 Unlimited Game Jacoby Beaver pip: 150 score: 0 Blue is Player 1
XGID=a-a-BBBBA---BAA-aacbbbbAA-:0:0:-1:21:0:0:3:0:10
32S-43H-22E-22E-54@-44S-41U-51r-52R-11B-31P-32N-31D-65S- F-66D-63H-F-11D-426-63r-21K-53-11A.-21-54J-528-21

1.	Rollout1	Bar/22	eq: -0.377
	Player: Opponent: 39.08% (G:16.68% B:1.30%) 60.92% (G:17.93% B:0.98%) Conf.: ± 0.008 (-0.384...-0.369) - [100.0%] Duration: 32 minutes 36 seconds
2.	Rollout1	Bar/24 8/6	eq: -0.479 (-0.103)
	Player: Opponent: 35.34% (G:15.83% B:1.00%) 64.66% (G:16.76% B:0.79%) Conf.: ± 0.008 (-0.488...-0.471) - [0.0%] Duration: 34 minutes 36 seconds
3.	Rollout1	Bar/24 7/5	eq: -0.577 (-0.200)
	Player: Opponent: 33.00% (G:14.87% B:0.99%) 67.00% (G:20.24% B:1.34%) Conf.: ± 0.012 (-0.589...-0.565) - [0.0%] Duration: 32 minutes 12 seconds
4.	Rollout1	Bar/23 9/8	eq: -0.584 (-0.207)
	Player: Opponent: 33.00% (G:13.81% B:1.05%) 67.00% (G:17.44% B:0.72%) Conf.: ± 0.008 (-0.592...-0.576) - [0.0%] Duration: 30 minutes 17 seconds
5.	Rollout1	Bar/23 3/2*	eq: -0.672 (-0.296)
	Player: Opponent: 31.95% (G:15.53% B:2.54%) 68.05% (G:28.03% B:2.26%) Conf.: ± 0.010 (-0.682...-0.662) - [0.0%] Duration: 33 minutes 27 seconds
6.	Rollout1	Bar/24 9/7	eq: -0.723 (-0.346)
	Player: Opponent: 30.84% (G:12.57% B:0.86%) 69.16% (G:20.21% B:1.09%) Conf.: ± 0.011 (-0.734...-0.712) - [0.0%] Duration: 30 minutes 01 second
7.	Rollout1	Bar/24 4/2*	eq: -0.744 (-0.367)
	Player: Opponent: 32.19% (G:16.16% B:2.62%) 67.81% (G:30.05% B:3.87%) Conf.: ± 0.010 (-0.754...-0.734) - [0.0%] Duration: 33 minutes 39 seconds
1 5184 Games rolled with Variance Reduction. Dice Seed: 85576101 Moves: 3-ply, cube decisions: XG Roller

In this post, two checker-play problems were posed:

(a) How should White play 21?

All three respondents correctly supported U (Up, bar/22) as White's best move. Indeed, it is a "wipeout" (opposite of a whopper, by the B/W error scale), as the rollout above shows.

Making the six-point prime is not even the second best play. It is fourth best and a double-whopper! Keeping the back men split, thereby creating more numbers to advance the back checker(s) and/or escape the prime in upcoming turns, does better.

After White correctly plays U, Blue stands better but is nowhere near a double. [White can also deflect a double (barely) if she makes the prime; that play is non-volatile though lame by comparison.]

(b) How should White play 42?

For this second checker-play problem (from the same board position), only kruidenbuiltje backed the correct answer. If White plays passively, she is badly outtimed in the priming battle. This situation calls for desperate measures, as the first rollout below demonstrates. The second and third rollouts are for the other two cube positions.

Blue should double/redouble (and it's a take) whichever 4 White plays. Due to the volatility, Blue's redouble is more correct when White hits, but it is in this way that White salvages the smallest negative equity.

.

		White is Player 2 score: 0 pip: 122 Unlimited Game Jacoby Beaver pip: 150 score: 0 Blue is Player 1
XGID=a-a-BBBBA---BAA-aacbbbbAA-:0:0:-1:42:0:0:3:0:10
32S-43H-22E-22E-54@-44S-41U-51r-52R-11B-31P-32N-31D-65S- F-66D-63H-F-11D-426-63r-21K-53-11A.-21-54J-528-42 White to play 42: Cube in center

1.	Rollout1	Bar/23 6/2*	eq: -0.765
	Player: Opponent: 30.17% (G:15.79% B:2.72%) 69.83% (G:28.32% B:2.17%) Conf.: ± 0.009 (-0.773...-0.756) - [100.0%] Duration: 1 hour 23 minutes
2.	Rollout1	Bar/23 8/4	eq: -0.812 (-0.048)
	Player: Opponent: 28.62% (G:11.91% B:0.69%) 71.38% (G:18.45% B:0.84%) Conf.: ± 0.010 (-0.822...-0.802) - [0.0%] Duration: 1 hour 10 minutes
3.	Rollout1	Bar/23 9/5	eq: -0.848 (-0.083)
	Player: Opponent: 28.17% (G:11.79% B:0.73%) 71.83% (G:19.42% B:0.89%) Conf.: ± 0.010 (-0.858...-0.838) - [0.0%] Duration: 1 hour 07 minutes
4.	Rollout1	Bar/23 5/1*	eq: -0.870 (-0.105)
	Player: Opponent: 28.58% (G:15.80% B:2.51%) 71.42% (G:30.20% B:2.53%) Conf.: ± 0.015 (-0.885...-0.854) - [0.0%] Duration: 1 hour 51 minutes
1 5184 Games rolled with Variance Reduction. Dice Seed: 85576101 Moves: 3-ply, cube decisions: XG Roller

ROLLOUT+C

		White is Player 2 score: 0 pip: 122 Unlimited Game Jacoby Beaver pip: 150 score: 0 Blue is Player 1
XGID=a-a-BBBBA---BAA-aacbbbbAA-:1:-1:-1:42:0:0:3:0:10
White to play 42: White owns cube

1.	Rollout1	Bar/23 6/2*	eq: -0.377
	Player: Opponent: 30.36% (G:15.84% B:2.77%) 69.64% (G:28.09% B:2.20%) Conf.: ± 0.004 (-0.381...-0.372) - [100.0%] Duration: 1 hour 21 minutes
2.	Rollout1	Bar/23 8/4	eq: -0.406 (-0.029)
	Player: Opponent: 28.70% (G:12.03% B:0.70%) 71.30% (G:18.67% B:0.84%) Conf.: ± 0.005 (-0.411...-0.401) - [0.0%] Duration: 1 hour 12 minutes
3.	Rollout1	Bar/23 5/1*	eq: -0.426 (-0.049)
	Player: Opponent: 28.64% (G:16.03% B:2.64%) 71.36% (G:30.23% B:2.37%) Conf.: ± 0.008 (-0.434...-0.417) - [0.0%] Duration: 1 hour 49 minutes
4.	Rollout1	Bar/23 9/5	eq: -0.430 (-0.054)
	Player: Opponent: 28.02% (G:11.60% B:0.73%) 71.98% (G:19.30% B:0.84%) Conf.: ± 0.005 (-0.435...-0.425) - [0.0%] Duration: 1 hour 06 minutes
1 5184 Games rolled with Variance Reduction. Dice Seed: 49207271 Moves: 3-ply, cube decisions: XG Roller

		White is Player 2 score: 0 pip: 122 Unlimited Game Jacoby Beaver pip: 150 score: 0 Blue is Player 1
XGID=a-a-BBBBA---BAA-aacbbbbAA-:1:1:-1:42:0:0:3:0:10
White to play 42: Blue owns cube

1.	Rollout1	Bar/23 6/2*	eq: -0.753
	Player: Opponent: 30.37% (G:15.84% B:2.77%) 69.63% (G:28.09% B:2.21%) Conf.: ± 0.009 (-0.762...-0.744) - [100.0%] Duration: 56 minutes 02 seconds
2.	Rollout1	Bar/23 8/4	eq: -0.783 (-0.030)
	Player: Opponent: 29.05% (G:12.08% B:0.72%) 70.95% (G:18.38% B:0.75%) Conf.: ± 0.007 (-0.790...-0.776) - [0.0%] Duration: 59 minutes 33 seconds
3.	Rollout1	Bar/23 9/5	eq: -0.860 (-0.107)
	Player: Opponent: 28.02% (G:11.60% B:0.73%) 71.98% (G:19.30% B:0.84%) Conf.: ± 0.010 (-0.870...-0.850) - [0.0%] Duration: 50 minutes 57 seconds
4.	Rollout2	Bar/23 5/1*	eq: -0.878 (-0.125)
	Player: Opponent: 28.43% (G:15.88% B:2.60%) 71.57% (G:30.14% B:2.39%) Conf.: ± 0.016 (-0.895...-0.862) - [0.0%] Duration: 38 minutes 59 seconds
1 5184 Games rolled with Variance Reduction. Dice Seed: 49207271 Moves: 3-ply, cube decisions: XG Roller 2 5184 Games rolled with Variance Reduction. Dice Seed: 3541123 Moves: 3-ply, cube decisions: XG Roller

The situation above (with White to play 42) somewhat reminds me of the scenario illustrated below that arose 13 years ago:

Pro-Am Finals
(Las Vegas, March 4th, 2001)
Blue: Nack Ballard + Harvey Huie
White: Mike Senkiewicz + Mike Sherman
Blue trails 14–15 to 23

		White is Player 2 score: 15 pip: 100 23 point match pip: 118 score: 14 Blue is Player 1
XGID=--BBa-DBBa---A--A-acdcb--A:1:1:1:32:14:15:0:23:10
Blue to play 32

Entering with the deuce is forced. With the 3, the choice is (a) to button up with 16/13, leaving just one blot, or (b) to hit with 7/4*, leaving five blots. Our choice of (b) was rewarded when our poor opponents rolled 22 (fanning). We won a redoubled gammon (reaching Crawford) and subsequently the match.

Sometimes the best chance to escape a fire is to hurl yourself through it.

Nack

Messages In This Thread

• Prime-versus-Prime, challenge #2
  Nack Ballard -- Thursday, 4 September 2014, at 4:52 a.m.
  • Prime-versus-Prime, challenge #2
    Ian Dunstan -- Thursday, 4 September 2014, at 8:01 a.m.
  • Prime-versus-Prime, challenge #2
    Joe Russell -- Thursday, 4 September 2014, at 8:49 a.m.
  • Prime-versus-Prime, challenge #2
    kruidenbuiltje -- Thursday, 4 September 2014, at 9:32 a.m.
    • Prime-versus-Prime, challenge #2
      Joe Russell -- Thursday, 4 September 2014, at 11:27 p.m.
  • Prime-versus-Prime, challenge #2, ROLLOUTS
    Nack Ballard -- Saturday, 18 October 2014, at 4:25 p.m.
    • Prime-versus-Prime, challenge #2, ROLLOUTS
      Ian Dunstan -- Sunday, 19 October 2014, at 1:13 a.m.